Molecular Cloning & Purification Of Myoglobin In Yak And Corresponding Energy Metabolism Pilot Study

To investigate the molecular mechanism for yak to adapt the hypoxia ennviroment of Qinghai-Tibetan plateu, experiment was carried out to clone yak myoglobin gene, to purify myoglobin from yak heat muscle and to measure myoglobin concentration, activities of lactate dehydtogenase(LDH) and malate dehydrogenase(MDH) in heart and skeleton muscles of yak, bufflo, and yellow cattle.The full-length coding sequence of myoglobin was obtained by RT-PCR using total RNA extracted from heart muscle tissues of Maiwa yak. The primers were designed based on bovine myoglobin gene sequence. The amlplified 640bp yak myoglobin gene shares 99.5% homology with that of bovine.Myoglobin was purified from yak heart muscle by salting-out, CM-Sephadex cation exchange chromatography, and Sephadex G-50 gel chromatography. The molecular weight of purified yak myoglobin was approcimately 17ku as shown on SDS-gel.Myoglobin content was assayed in yak and compared with those of bufflo and yellow cattle. Yak heart muscle and skeleton muscle contained significantly higher concentration of myoglobin than bufflo and yellow cattle(P<0.01); Heart tissue contained significantly higher content of myoglobin than skeleton muscle in the same individual(P<0.01), Activities of LDH and MDH in heart and skeleton muscle of yak were significantly lower than those of bufflo and yellow cattle. Activity of LDH and MDH in heart tissue was significantly lower and higher respectively than that in skeleton muscle of the same individual. There existed significant negetive relationship between myoglobin content and LDH activity, positive relationship between myoglobin content and MDH activity and MDH/LDH ratio in heart and skeleton muscle...